i love them so much but im so scared

my partner is so perfect theyre always worryingabout me and ready to communicate when either of us are uncomfortable theyre so understanding and wonderful and pretty but im so scared because what if its all fake? what if they secretly hate me and just want me to die so they dont have to pretend to worry about me anymore? i psuhthem away because of this but i just want to lavish them with love and suffocate them with my affection but i cant bring myself to because i dont believe they love me. its such a hard feeling. we‘ve been having serious conversations and arguments non-stop about it because my foolish self decided to question them about it. they keep insisting the truth is that they love me but i just cant believe it.. i feel so badd… i love my partner so much i dont deserve someone like them but at the same time i cant bear to see them with someone else. if i saw them being all lovey-dovey with another person i think id lose it i cant even think about it. it makes me wanna throw up i dont want to lose them but i dont know what to do.